1. Field of the Invention
The invention relates generally to data-processing systems and more specifically to floating-point units utilized by such systems to perform arithmetic operations on floating-point data.
2. Description of Prior Art
In the prior art, floating-point units have been constructed for performing arithmetic operations on single-precision floating-point data, double-precision floating-point data, or either single-precision floating-point data or double-precision floating-point data. Such floating-point units contain registers for storing floating-point data being processed, logic for processing the sign and exponent parts of floating-point data, mantissa arithmetic units for processing the mantissa, and logic for providing status signals to the processor controlling the floating-point unit.
Floating-point units for operating only on single-precision floating point data have been constructed on a single module such as a printed circuit board; those for operating on double-precision floating-point data or both single- and double-precision floating-point data have been constructed using two modules, one containing registers for the sign, exponent, and part of the mantissa of the double-precision floating point data, the logic for processing the sign and exponent, a mantissa arithmetic unit for processing that portion of the mantissa stored on the module and the logic providing status signals to the processor controlling the floating-point unit. The other module in such floating-point units contains registers for storing the remaining part of the mantissa and a mantissa arithmetic unit.
The requirement that a double-precision floating-point unit be made up of two different modules has increased the complexity of digital data processing systems and has thereby increased the cost of manufacturing such systems, of servicing such systems, and of maintaining parts inventories for manufacture and repair. This problem of prior-art floating-point units and others as well are remedied by the present invention.